Origin combinations, how organic the world building is. Im so use to many other FVNs it's MC doing a mix of narration/inner monologue often being one in the same sentence to give context to the reader, tho in universe that doesnt make any sense. This game doesn't do that thankfully, it actually conveys context correctly. Each character is has an expertise in a subject, while others won't, so they'll explain it to them in-game cuz they genuinely don't know. This is how us the reader learns about game's world in universe again, in a very organic realistic way. I cannot stress how meticulously detailed all of this is done, on top of dialogue choices, origin combinations changing roughly 80% of what you'd think be the same scene damn near entirely.
The replay value is absolutely massive, and yet the continuity stays consistent for that playthrough. I'm just so enthralled with its world. My only grip is there isn't an in-game wiki for all these terminologies to keep track of. Thankfully there is a Stats to show your origin combo, skills and affinity for the crewmates, much appreciated.
Edit: I forgot to mention how wonderfully expressive the character sprites are even moving their mouths and tails too to properly convey their excitement